Components and catalysts for the polymerization of olefins

ABSTRACT

The present invention relates to a solid catalyst component for the polymerization of olefins CH 2 ═CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, halogen and an electron donor selected from succinates, said catalyst component being obtainable by a process comprising the following steps: (a) dissolving a halide of magnesium in a solvent system comprising an organic epoxy compound or an organic phosphorus compound and optionally an inert diluent to form a solution; (b) mixing the obtained solution with a titanium compound to form a mixture; (c) precipitating a solid from the mixture obtained in step (b) in the presence of a succinate and/or an auxiliary precipitant; (d) if a succinate is not used in step (c), contacting the solid obtained in (c) with a succinate, and (e) treating the solid obtained in (c) or (d) with a titanium compound optionally in the presence of an inert diluent.

The present invention relates to catalyst components for thepolymerization of olefins, to the catalyst obtained therefrom and to theuse of said catalysts in the polymerization of olefins CH₂═CHR in whichR is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms. Inparticular the present invention relates to catalyst components,suitable for the stereospecific polymerization of olefins, comprisingTi, Mg, halogen and an electron donor compound selected from esters ofsuccinic acids (hereinafter succinates) obtained by a specific process.Said catalyst components when used in the polymerization of olefins, andin particular of propylene, are capable to give polymers in higheryields with respect to those obtainable with the succinate basedcatalysts of the prior art.

High-yield catalyst components for the polymerization of olefins, and inparticular for propylene, are known in the art. They are generallyobtained by supporting, on a magnesium dihalide, a titanium compound andan electron donor compound as a selectivity control agent. Said catalystcomponents are then used together with an aluminum alkyl and,optionally, another electron donor (external) compound in thestereospecific polymerization of propylene. Depending on the type ofelectron donor used, the activity and stereospecificity of the catalystcan vary. The catalyst components that comprise phthalates as internaldonors and silanes as external donors show a very high catalyticactivity, generally above 2000 kg of polymer per g of titanium. The useof certain specific catalyst preparations however, such as thosedisclosed in U.S. Pat. No. 4,784,983, can lead to a lower activity.Furthermore, the propylene polymers obtained with the phthalatecontaining catalyst systems usually have a narrow molecular weightdistribution (MWD) as compared for example with the propylene polymersprepared by using the conventional catalysts comprising a titaniumtrichloride based catalyst component. The narrow MWD causes a worseningof the processability of the polymers which involves a decrease of thequality of the products in applications such as molding orthermoforming. WO00/63261 discloses the use of catalyst components,suitable for the stereospecific polymerization of olefins, comprisingTi, Mg, halogen and an internal electron donor compound selected fromesters of substituted succinic acids (substituted succinates). Thesecatalyst components used in combination with silanes as external donorsallow the preparation of stereoregular propylene polymers with broadMWD. The activities, although of interest, are in certain cases lowerthan 2000 kg of polymer per g of titanium. It would be therefore desiredto have available catalyst components containing succinates as internaldonors and endowed with an improved catalytic activity.

The applicant has surprisingly found a solid catalyst component thatmeets the requirements which comprises titanium, magnesium, halogen anda succinate and is obtainable by a process comprising the followingsteps:

-   (a) dissolving a halide of magnesium in a solvent system comprising    an organic epoxy compound or an organic phosphorus compound and    optionally an inert diluent to form a solution;-   (b) mixing the obtained solution with a titanium compound to form a    mixture;-   (c) precipitating a solid from the mixture obtained in step (b) in    the presence of a succinate and/or an auxiliary precipitant;-   (d) if a succinate is not used in step (c), contacting the solid    obtained in (c) with a succinate, and-   (e) treating the solid obtained in (c) or (d) with a titanium    compound optionally in the presence of an inert diluent.

The solution disclosed in (a) is obtained by dissolving a halide ofmagnesium in a solvent system comprising an organic epoxy compounds ororganic phosphorus compounds. The solvent system may include inertdiluents. According to the present invention the term halide ofmagnesium include magnesium dihalides such as magnesium dichloride,magnesium dibromide and magnesium diiodide; complexes of magnesiumdihalide with Lewis base such as water or alcohol, and derivatives ofmagnesium halide wherein a halogen atom is substituted by ahydrocarboxyl or halohydrocarboxyl group.

Suitable organic epoxy compounds include oxides of aliphatic olefins,aliphatic diolefins, halogenated aliphatic olefins, and halogenatedaliphatic diolefins, glycidyl ethers, cyclic ethers and the like having2-8 carbon atoms. Examples of suitable organic epoxy compounds areethylene oxide, propylene oxide, butylene oxide, butadiene dioxide,epoxy chloropropane, methylglycidyl ether, diglycidyl ether,tetrahydrofuran, and the like.

Suitable organic phosphorous compounds include hydrocarbon esters ofphosphoric acids such as trimethyl phosphate, triethyl phosphate,tributyl phosphate, triphenyl phosphate, trimethyl phosphate; trimethylphosphate, triethyl phosphate and tributyl phosphate are preferred whiletributyl phosphate is the most preferred.

The particle size of the halide of magnesium used is preferred to besuch that it is easily dissolved with stirring. The dissolutiontemperature is from about 0° to about 100° C., preferably from 30° C. to70° C. Inert diluents such as hexane, heptane, octane, benzene, toluene,xylene, 1,2-dichloroethane, chlorobenzene and other hydrocarbons orhalohydrocarbons can be added into the solvent system. The amount ofepoxy compounds added is about 0.2-10.0 moles, preferably 0.54.0 moles,per mole of halide of magnesium, and the amount of organic phosphoruscompounds added is about 0.1-3.0 moles, preferably 0.3-1.0 moles, permole of halide of magnesium.

The solution of magnesium halide is mixed with liquid titaniumtetrahalide to form a solid precipitate in the presence of an auxiliaryprecipitant. The succinate may be added before or after theprecipitation of the solid and loaded on the solid.

According to the invention, the auxiliary precipitant can be addedeither after the halide of magnesium solution is obtained or togetherwith the halide of magnesium. The liquid titanium tetrahalide or itsderivatives can be in the pure liquid state, or in a solution of inertdiluents.

The titanium compound used in the preparation of the solid catalystcomponent (A) of the invention is preferably a compound having theformula TiX_(n)(OR)_(4-n) wherein X is a halogen, preferably chlorine,each R is independently a hydrocarbyl group and n is an integer of from0 to 4. Examples of preferred titanium compounds are titaniumtetrachloride, titanium tetrabromide, titanium tetraiodide, tetrabutoxytitanium, tetraethoxy titanium, chlorotriethoxy titanium,dichlorodiethoxy titanium, trichloroethoxy titanium and the like.

Examples of the solution of magnesium halide and the liquid titaniumtetrahalide or its derivatives used in the present invention have beendisclosed in U.S. Pat. No. 4,784,983 the relevant part of which isincorporated herein by reference.

The auxiliary precipitant according to this invention includes organicacid anhydrides, organic acids, ketones, aldehydes, ethers and anycombination thereof, such as acetic anhydride, phthalic anhydride,succinic anhydride, maleic anhydride, pyromellitic dianhydride, aceticacid, propionic acid, butyric acid, acrylic acid, methacrylic acid,acetone, methyl ethyl ketone, benzophenone, dimethyl ether, diethylether, dipropyl ether, dibutyl ether, diamyl ether, 1,3-diethers,succinates and the like. As mentioned before, the step of treating thesolid with a succinate may be omitted when the auxiliary precipitantcomprises the succinate donor compound. The process of solidsprecipitation can be carried out by several methods. However,particularly preferred are two methods. One method involves mixingliquid titanium tetrahalide with a halide of magnesium at a temperaturein the range of about −40° C. to 0° C., and precipitating the solidswhile the temperature is raised slowly. The other preferred methodinvolves adding liquid titanium tetrahalide dropwise into thehomogeneous halide of magnesium solution at room temperature toprecipitate out solids immediately. In both methods, an auxiliaryprecipitant must be present in the reaction system. The auxiliaryprecipitant can be added before or after precipitation of the solidstarts.

In order to obtain uniform solid particles, the process of precipitationshould be carried out slowly. When the second method of adding titaniumhalide dropwise at room temperature is applied, the process shouldpreferably take place over a period of from about 1 hour to 6 hours.When the first method of raising the temperature in a slow manner isapplied, the rate of temperature increase preferably ranges from about4° C. to about 100° C. per hour.

The mole ratios of various components per mole of magnesium halide inthis step are as follow: titanium halide, 0.5-150, preferably 1-20 andauxiliary precipitant, 0.03-1.0, preferably 0.05-1.4.

As mentioned before, if the auxiliary precipitant is not a succinate theprecipitated solid must be treated with a succinate. Particularlysuitable succinates are those of formula (I):

wherein the radicals R₁ and R₂, equal to, or different from, each otherare a C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl,arylalkyl or alkylaryl group, optionally containing heteroatoms; theradicals R₃ to R₆ equal to, or different from, each other, are hydrogenor a C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl,arylalkyl or alkylaryl group, optionally containing heteroatoms, and theradicals R₃ to R₆ can be linked together to form a cycle.

R₁ and R₂ are preferably C₁-C₈ alkyl, cycloalkyl, aryl, arylalkyl andalkylaryl groups. Particularly preferred are the compounds in which R₁and R₂ are selected from primary alkyls and in particular branchedprimary alkyls. Examples of suitable R₁ and R₂ groups are methyl, ethyl,n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl. Particularlypreferred are ethyl, isobutyl, and neopentyl.

One of the preferred groups of compounds described by the formula (I) isthat in which R₃ to R₅ are hydrogen and R₆ is a branched alkyl,cycloalkyl, aryl, arylalkyl and alkylaryl radical having from 3 to 10carbon atoms. Particularly preferred are the compounds in which R₆ is abranched primary alkyl group or a cycloalkyl group having from 3 to 10carbon atoms.

Specific examples of suitable monosubstituted succinate compounds areDiethyl sec-butylsuccinate, Diethyl thexylsuccinate, Diethylcyclopropylsuccinate, Diethyl norbornylsuccinate, Diethylperihydrosuccinate, Diethyl trimethylsilylsuccinate, Diethylmethoxysuccinate, Diethyl p-methoxyphenylsuccinate, Diethylp-chlorophenylsuccinate diethyl phenylsuccinate, diethylcyclohexylsuccinate, diethyl benzylsuccinate, diethylcyclohexylmethylsuccinate, diethyl t-butylsuccinate, diethylisobutylsuccinate, diethyl isopropylsuccinate, diethylneopentylsuccinate, diethyl isopentylsuccinate, diethyl(1-trifluoromethylethyl)succinate, diethyl fluorenylsuccinate,1-(ethoxycarbo diisobutyl phenylsuccinate, Diisobutylsec-butylsuccinate, Diisobutyl thexylsuccinate, Diisobutylcyclopropylsuccinate, Diisobutyl norbornylsuccinate, Diisobutylperihydrosuccinate, Diisobutyl trimethylsilylsuccinate, Diisobutylmethoxysuccinate, Diisobutyl p-methoxyphenylsuccinate, Diisobutylp-chlorophenylsuccinate, diisobutyl cyclohexylsuccinate, diisobutylbenzylsuccinate, diisobutyl cyclohexylmethylsuccinate, diisobutylt-butylsuccinate, diisobutyl isobutylsuccinate, diisobutylisopropylsuccinate, diisobutyl neopentylsuccinate, diisobutylisopentylsuccinate, diisobutyl (1-trifluoromethylethyl)succinate,diisobutyl fluorenylsuccinate, Dineopentyl sec-butylsuccinate,Dineopentyl thexylsuccinate, Dineopentyl cyclopropylsuccinate,Dineopentyl norbornylsuccinate, Dineopentyl perihydrosuccinate,Dineopentyl trimethylsilylsuccinate, Dineopentyl methoxysuccinate,Dineopentyl p-methoxyphenylsuccinate, Dineopentylp-chlorophenylsuccinatedineopentyl phenylsuccinate, dineopentylcyclohexylsuccinate, dineopentyl benzylsuccinate, dineopentylcyclohexylmethylsuccinate, dineopenthyl t-butylsuccinate, dineopentylisobutylsuccinate, dineopentyl isopropylsuccinate, dineopentylneopentylsuccinate, dineopentyl isopentylsuccinate, dineopentyl(1-trifluoromethylethyl)succinate, dineopentyl fluorenylsuccinate.

Another preferred group of compounds within those of formula (I) is thatin which at least two radicals from R₃ to R₆ are different from hydrogenand are selected from C₁-C₂₀ linear or branched alkyl, alkenyl,cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containingheteroatoms. Particularly preferred are the compounds in which the tworadicals different from hydrogen are linked to the same carbon atomSpecific examples of suitable disubstituted succinates are: diethyl2-,2-dimethylsuccinate, diethyl 2-ethyl-2-methylsuccinate, diethyl2-Benzyl-2-isopropylsuccinate, Diethyl2-cyclohexylmethyl-2-isobutylsuccinate, Diethyl 2-cyclopentyl-2-n-butylsuccinate, Diethyl 2,2-diisobutylsuccinate, Diethyl2-cyclohexyl-2-ethylsuccinate, Diethyl 2-isopropyl-2-methylsuccinate,Diethyl 2-tetradecyl-2 ethyl succinate, Diethyl2-isobutyl-2-ethylsuccinate, Diethyl2-(1-trifluoromethyl-ethyl)-2-methylsuccinate, Diethyl2-isopentyl-2-isobutylsuccinate, Diethyl 2-phenyl 2-n-butylsuccinate,diisobutyl 2-,2-dimethylsuccinate, diisobutyl 2-ethyl-2-methylsuccinate,Diisobutyl 2-benzyl-2 isopropylsuccinate, Diisobutyl2-cyclohexylmethyl-2-isobutylsuccinate, Diisobutyl2-cyclopentyl-2-n-butylsuccinate, Diisobutyl 2,2-diisobutylsuccinate,Diisobutyl 2-cyclohexyl-2-ethylsuccinate, Diisobutyl2-isopropyl-2-methylsuccinate, Diisobutyl 2-tetradecyl-2-ethylsuccinate,Diisobutyl 2-isobutyl-2-ethylsuccinate, Diisobutyl2-(1-trifluoromethyl-ethyl)-2-methylsuccinate, Diisobutyl2-isopentyl-2-isobutylsuccinate, Diisobutyl 2-phenyl 2-nButyl-succinate,dineopentyl 2-,2-dimethylsuccinate, dineopentyl2-ethyl-2-methylsuccinate, Dineopentyl 2-Benzyl-2 isopropylsuccinate,Dineopentyl 2-cyhexylmethyl-2-isobutylsuccinate, Dineopentyl2-cyclopentyl-2-n-butylsuccinate, Dineopentyl 2,2-diisobutylsuccinate,Dineopentyl 2-cyclohexyl-2-ethylsuccinate, Dineopentyl2-isopropyl-2-methylsuccinate, Dineopentyl 2-tetradecyl-2ethylsuccinate, Dineopentyl 2-isobutyl-2-ethylsuccinate, Dineopentyl2-(1-trifluoromethyl-ethyl)-2-methylsuccinate, Dineopentyl2-isopentyl-2-isobutylsuccinate, Dineopentyl 2-phenyl2-n-butylsuccinate.

Furthermore, also the compounds in which at least two radicals differentfrom hydrogen are linked to different carbon atoms, that is R₃ and R₅ orR₄ and R₆ are particularly preferred. Specific examples of suitablecompounds are Diethyl 2,3bis(trimethylsilyl)succinate, Diethyl2,2-secbutyl-3-methylsuccinate, Diethyl2-(3,3,3,trifluoropropyl)-3-methylsuccinate, Diethyl 2,3bis(2-ethyl-butyl)succinate, Diethyl 2,3-diethyl-2-isopropylsuccinate,Diethyl 2,3-diisopropyl-2-methylsuccinate, Diethyl2,3-dicyclohexyl-2-methyl diethyl 2,3-dibenzylsuccinate, diethyl2,3-diisopropylsuccinate, diethyl 2,3-bis(cyclohexylmethyl)succinate,Diethyl 2,3-di-t-butylsuccinate, Diethyl 2,3-diisobutylsuccinate,Diethyl 2,3-di neopentylsuccinate, Diethyl 2,3-diisopentylsuccinate,Diethyl 2,3-(1-trifluoromethyl-ethyl)succinate, Diethyl2,3-tetradecylsuccinate, Diethyl 2,3-fluorenylsuccinate, Diethyl2-isopropyl-3-isobutylsuccinate, Diethyl2-terbutyl-3-isopropylsuccinate, Diethyl2-ipropyl-3-cyclohexylsuccinate, Diethyl2-isopentyl-3-cyclohexylsuccinate, Diethyl2-tetradecyl-3-cyclohexylmethylsuccinate, Diethyl2-cyclohexyl-3-cyclopentylsuccinate, Diethyl2,2,3,3-tetramethylsuccinate, Diethyl 2,2,3,3-tetraethylsuccinate,Diethyl 2,2,3,3 tetrapropylsuccinate, Diethyl2,3-diethyl-2,3-diisopropylsuccinate, Diethyl 2,2,3,3tetrafluorosuccinate, Diisobutyl 2,3bis(trimethylsilyl)succinate,Diisobutyl 2,2-secbutyl-3-methylsuccinate, Diisobutyl2-(3,3,3,trifluoropropyl)-3-methylsuccinate, Diisobutyl 2,3bis(2-ethyl-butyl)succinate, Diisobutyl2,3-diethyl-2-isopropylsuccinate, Diisobutyl2,3-diisopropyl-2-methylsuccinate, Diisobutyl 2,3-dicyclohexyl-2-methyl,diisobutyl 2,3-dibenzylsuccinate, diisobutyl 2,3-diisopropylsuccinate,diisobutyl 2,3-bis(cyclohexylmethyl)succinate, Diisobutyl2,3-di-t-butylsuccinate, Diisobutyl 2,3-diisobutylsuccinate, Diisobutyl2,3-dineopentylsuccinate, Diisobutyl 2,3-diisopentylsuccinate,Diisobutyl 2,3-(1-trifluoromethyl-ethyl)succinate, Diisobutyl2,3-tetradecylsuccinate, Diisobutyl 2,3-fluorenylsuccinate, Diisobutyl2-ipropyl-3-ibutylsuccinate, Diisobutyl 2-terbutyl-3-ipropylsuccinate,Diisobutyl 2-ipropyl-3-cyclohexylsuccinate, Diisobutyl2-isopentyl-3-cyclohexylsuccinate, Diisobutyl2-tetradecyl-3-cyclohexylmethylsuccinate, Diisobutyl2-cyclohexyl-3-cyclopentylsuccinate, Diisobutyl2,2,3,3-tetramethylsuccinate, Diisobutyl 2,2,3,3-tetraethylsuccinate,Diisobutyl 2,2,3,3 tetrapropylsuccinate, Diisobutyl2,3-diethyl-2,3-diisopropylsuccinate, Diisobutyl 2,2,3,3tetrafluorosuccinate Dineopentyl 2,3bis(trimethylsilyl)succinate,Dineopentyl 2,2-secbutyl-3-methylsuccinate, Dineopentyl2-(3,3,3,trifluoropropyl)-3-methylsuccinate, Dineopentyl 2,3bis(2-ethyl-butyl)succinate, Dineopentyl2,3-diethyl-2-isopropylsuccinate, Dineopentyl2,3-diisopropyl-2-methylsuccinate, Dineopentyl2,3-dicyclohexyl-2-methyl, dineopentyl 2,3-dibenzylsuccinate,dineopentyl 2,3-diisopropylsuccinate, dineopentyl2,3-bis(cyclohexylmethyl)succinate, Dineopentyl 2,3-di-t-butylsuccinate,Dineopentyl 2,3-diisobutylsuccinate, Dineopentyl2,3-dineopentylsuccinate, Dineopentyl 2,3-diisopentylsuccinate,Dineopentyl 2,3-(1-trifluoromethyl-ethyl)succinate, Dineopentyl2,3-tetradecylsuccinate, Dineopentyl 2,3-fluorenylsuccinate, Dineopentyl2-ipropyl-3-ibutylsuccinate, Dineopentyl2-terbutyl-3-isopropylsuccinate, Dineopentyl2-isopropyl-3-cyclohexylsuccinate, Dineopentyl2-isopentyl-3-cyclohexylsuccinate, Dineopentyl2-tetradecyl-3-cyclohexylmethyl succinate, Dineopentyl2-cyclohexyl-3-cyclopentylsuccinate, Dineopentyl2,2,3,3-tetramethylsuccinate, Dineopentyl 2,2,3,3-tetraethylsuccinate,Dineopentyl 2,2,3,3 tetrapropylsuccinate, Dineopentyl2,3-diethyl-2,3-diisopropylsuccinate, Dineopentyl 2,2,3,3tetrafluorosuccinate.

As mentioned above the compounds according to formula (I) in which twoor four of the radicals R₃ to R₆ which are joined to the same carbonatom are linked together to form a cycle are also preferred.

Specific examples of suitable compounds are1-(ethoxycarbonyl)-1-(Ethoxyacetyl)-2,6-dimethyl cyclohexane,1-(ethoxycarbonyl)-1-(Ethoxyacetyl)-2,5-dimethyl cyclopentane,1-(ethoxycarbonyl)-1-(Ethoxyacetylmethyl)-2-methyl cyclohexane,1-(ethoxycarbonyl)-1-(Ethoxyacetylcyclohexyl) cyclohexane.

It is easily derivable for the ones skilled in the art that all theabove mentioned compounds can be used either in form of pure isomers orin the form of mixtures of enantiomers, or mixture of regioisomers andenantiomers. When a pure isomer is to be used it is normally isolatedusing the common techniques known in the art. In particular some of thesuccinates of the present invention can be used as a pure rac or mesoforms or, in alternative, as a mixture of these two forms.

The succinate treated solid precipitate is first separated from themixture. In the solid precipitate thus obtained can be entrained avariety of complexes and impurities, so that further treatment may benecessary. Accordingly, the solid precipitates are treated with atitanium compound, preferably titanium tetrahalide or a mixture oftitanium tetrahalide and an inert diluent, and then washed with an inertdiluent. The amount of titanium compound used is 1 to 20 moles,preferably 2 to 15 moles, per mole of halide of magnesium. The treatmenttemperature ranges from 50° C. to 150° C., preferably from 60° C. to100° C. If a mixture of titanium tetrahalide and inert diluent is usedto treat the solid precipitate, the amount of titanium tetrahalide inthe treating solution is 10-99 percent by vol., preferably 20-80percent, the rest being an inert diluent. The treated solids are furtherwashed with an inert diluent to remove ineffective titanium compoundsand other impurities.

The catalyst component (A) according to the present invention which isobtained through the above described steps can be used as a solid or asa suspension.

The solid catalyst components (A) according to the present invention areconverted into catalysts for the polymerization of olefins by reactingthem with (B) organoaluminum compounds according to known methods.

Preferred organoaluminum compounds are the alkyl-Al compounds which arepreferably selected from the trialkyl aluminum compounds such as forexample triethylaluminum, triisobutylaluminum, tri-n-butylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to usemixtures of trialkylaluminum's with alkylaluminum halides, alkylaluminumhydrides or alkylaluminum sesquichlorides such as AlEt₂Cl and Al₂Et₃Cl₃.In the catalyst system of the invention, the molar ratio of aluminium incomponent (B) to titanium in component (A) is from 5 to 1000, preferablyfrom 100 to 800, and the molar ratio of silicon in component (C) totitanium in component (A) is from 2 to 100, preferably from 8 to 32.

When polymers having a very high isotactic index are required the use ofan external donor compound is normally advisable. The external donor (C)can be of the same type or it can be different from the succinate offormula (I). Preferred external electron-donor compounds include siliconcompounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines,heterocyclic compounds and particularly 2,2,6,6-tetramethyl piperidine,ketones and the 1,3-diethers of the general formula (II):

wherein R^(I), R^(II), R^(III), R^(IV), R^(V) and R^(VI) equal ordifferent to each other, are hydrogen or hydrocarbon radicals havingfrom 1 to 18 carbon atoms, and R^(VII) and R^(VIII), equal or differentfrom each other, have the same meaning of R^(I)-R^(VI) except that theycannot be hydrogen; one or more of the R^(I)-R^(VIII) groups can belinked to form a cycle. Particularly preferred are the 1,3-diethers inwhich R^(VII) and R^(VIII) are selected from C₁-C₄ alkyl radicals.

Another class of preferred external donor compounds is that of siliconcompounds of formula R_(a) ⁵R_(b) ⁶Si(OR⁷)_(c), where a and b areinteger from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is4; R⁵, R⁶, and R⁷, are alkyl, cycloalkyl or aryl radicals with 1-18carbon atoms optionally containing heteroatoms. Particularly preferredare the silicon compounds in which a is 1, b is 1, c is 2, at least oneof R⁵ and R⁶ is selected from branched alkyl alkenyl, alkylen,cycloalkyl or aryl groups with 3-10 carbon atoms optionally containingheteroatoms and R⁷ is a C₁-C₁₀ alkyl group, in particular methyl.Examples of such preferred silicon compounds aremethylcyclohexyldimethoxysilane, diphenyldimethoxysilane,methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane,2-ethylpiperidinyl-2-t-butyldimethoxysilane and1,1,1,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane and1,1,1,trifluoropropyl-metil-dimethoxysilane. Moreover, are alsopreferred the silicon compounds in which a is 0, c is 3, R⁶ is abranched alkyl or cycloalkyl group, optionally containing heteroatoms,and R⁷ is methyl. Examples of such preferred silicon compounds arecyclohexyltrimethoxysilane, t-butyltrimethoxysilane andthexyltrimethoxysilane.

The electron donor compound (c) is used in such an amount to give amolar ratio between the organoaluminum compound and said electron donorcompound (c) of from 0.1 to 500, preferably from 1 to 300 and morepreferably from 3 to 100. As previously indicated, when used in the(co)polymerization of olefins, and in particular of propylene, thecatalysts of the invention allow to obtain, very high yields andpolymers endowed with a broad MWD.

As mentioned above all these catalysts can be used in the processes forthe polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms. The preferred alpha-olefinsto be (co)polymerized are ethylene, propylene,butene-1,4-methyl-1-pentene and hexene-1. In particular, the abovedescribed catalysts have been used in the (co)polymerization ofpropylene and ethylene to prepare different kinds of products. Forexample the following products can be prepared: high density ethylenepolymers (HDPE, having a density higher than 0.940 g/cm³), comprisingethylene homopolymers and copolymers of ethylene with alpha-olefinshaving 3-12 carbon atoms; linear low density polyethylenes (LLDPE,having a density lower than 0.940 g/cm³) and very low density and ultralow density (VLDPE and ULDPE, having a density lower than 0.920 g/cm³,to 0.880 g/cm³ cc) consisting of copolymers of ethylene with one or morealpha-olefins having from 3 to 12 carbon atoms, having a mole content ofunits derived from the ethylene higher than 80%; elastomeric copolymersof ethylene and propylene and elastomeric terpolymers of ethylene andpropylene with smaller proportions of a diene having a content by weightof units derived from the ethylene comprised between about 30 and 70%,isotactic polypropylenes and crystalline copolymers of propylene andethylene and/or other alpha-olefins having a content of units derivedfrom propylene higher than 85% by weight (random copolymers); shockresistant polymers of propylene obtained by sequential polymerization ofpropylene and mixtures of propylene with ethylene, containing up to 30%by weight of ethylene; copolymers of propylene and 1-butene having anumber of units derived from 1-butene comprised between 10 and 40% byweight.

Any kind of polymerization process can be used with the catalysts of theinvention that are very versatile. The polymerization can be carried outfor example in slurry using as diluent an inert hydrocarbon solvent, orin bulk using the liquid monomer (for example propylene) as a reactionmedium. Moreover, it is possible to carry out the polymerization processin gas-phase operating in one or more fluidized or mechanically agitatedbed reactors.

The catalyst of the present invention can be used as such in thepolymerization process by introducing it directly into the reactor. Inthe alternative, the catalyst can be pre-polymerized before beingintroduced into the first polymerization reactor. The termpre-polymerized as used in the art, means a catalyst which has beensubject to a polymerization step at a low conversion degree. Accordingto the present invention a catalyst is considered to be pre-polymerizedwhen the amount the polymer produced is from about 0.1 up to about 1000g per gram of solid catalyst component.

The pre-polymerization can be carried out with the alpha olefinsselected from the same group of olefins disclosed before. In particular,it is especially preferred pre-polymerizing ethylene or mixtures thereofwith one or more α-olefins in an amount up to 20% by mole. Preferably,the conversion of the pre-polymerized catalyst component is from about0.2 g up to about 500 g per gram of solid catalyst component.

The pre-polymerization step can be carried out at temperatures from 0 to80° C. preferably from 5 to 50° C. in liquid or gas-phase. Thepre-polymerization step can be performed in-line as a part of acontinuous polymerization process or separately in a batch process. Thebatch pre-polymerization of the catalyst of the invention with ethylenein order to produce an amount of polymer ranging from 0.5 to 20 g pergram of catalyst component is particularly preferred.

The polymerization is generally carried out at temperature of from 20 to120° C., preferably of from 40 to 80° C. When the polymerization iscarried out in gas-phase the operating pressure is generally between 0.5and 10 MPa, preferably between 1 and 5 MPa. In the bulk polymerizationthe operating pressure is generally between 1 and 6 MPa preferablybetween 1.5 and 4 MPa. Hydrogen or other compounds capable to act aschain transfer agents can be used to control the molecular weight ofpolymer.

The following examples are given in order to better illustrate theinvention without limiting it.

EXAMPLES

Characterization

Preparation of Succinates

Succinates can be prepared according to known methods described in theliterature, (see for example N. R. Long, M. W. Rathke, Synthetic commun.11, 687, 1981. M. W. Ratke, A. Lindert, J. Am. Chem. Soc. 93, 4605,1971).

Propylene Polymerization: General Procedure

In a 4 liter autoclave, purged with nitrogen flow at 70° C. for one our,75 ml of anhydrous hexane containing 800 mg of AlEt₃, 79.8 mg ofdicyclopentyldimethoxysilane and 10 mg of solid catalyst component wereintroduced in propylene flow at 30° C. The autoclave was closed. 1.5 Nlof hydrogen were added and then, under stirring, 1.2 Kg of liquidpropylene were fed. The temperature was raised to 70° C. in five minutesand the polymerization was carried out at this temperature for twohours. The nonreacted propylene was removed, the polymer was recoveredand dried at 70° C. under vacuum for three hours and, then, weighed andfractionated with o-xylene to determine the amount of the xyleneinsoluble (X.I.) fraction at 25° C.

Determination of X.I.

2.5 g of polymer were dissolved in 250 ml of o-xylene under stirring at135° C. for 30 minutes, then the solution was cooled to 25° C. and after30 minutes the insoluble polymer was filtered. The resulting solutionwas evaporated in nitrogen flow and the residue was dried and weighed todetermine the percentage of soluble polymer and then, by difference thexylene insoluble fraction (%).

Determination of Polydispersity Index “P.I.”

This property is strictly connected with the molecular weightdistribution of the polymer under examination. In particular it isinversely proportional to the creep resistance of the polymer in themolten state. Said resistance called modulus separation at low modulusvalue (500 Pa), was determined at a temperature of 200° C. by using aparallel plates rheometer model RMS-800 marketed by RHEOMETRICS (USA),operating at an oscillation frequency which increases from 0.1 rad/secto 100 rad/second. From the modulus separation value, one can derive theP.I. by way of the equation:P.I:=54.6*(modulus separation)^(−1.76)in which the modulus separation is defined as:modulus separation=frequency at G′=500 Pa/frequency at G″=500 Pawherein G′ is storage modulus and G″ is the loss modulus.

Example 1

Preparation of Solid Catalyst Component

Anhydrous magnesium chloride (5 g), toluene (100 ml), epoxychloropropane (EPC) (4 ml) and tributyl phosphate (TBP) (14 ml) wereintroduced into a reactor which has thoroughly been purged with highlypurified nitrogen. The temperature was raised to 50° C. with stirring,and the mixture was then maintained at that temperature for 3 hours,while the solids were dissolved completely. Phthalic anhydride (1.2 g)was added to the solution, and then the solution was maintained for anadditional 1 hour at 50° C. The solution was cooled to −25° C. Thentitanium tetrachloride (60 ml) was added dropwise over a course of 1hour while the mixture was kept under stirring. The solution was slowlyheated to 80° C., while a solid product is precipitated. Di-n-butylsuccinate (8 mmoles) was added and the mixture was maintained at thetemperature of 80° C. for 1 hour. The stirring was discontinued, theliquid portion siphoned off and the resulting solid portion wascollected by filtration and washed at 110° C. with toluene (2 times 100ml each). A brown-yellow solid precipitate was obtained. The solid wasthen dispersed in toluene (60 ml) and titanium tetrachloride (60 ml) for2 hours at 90° C. After that, the stirring was discontinued, the liquidportion siphoned off and the resulting solid portion was subject toanother treatment with toluene and titanium tetrachloride under the sameconditions. The solid obtained was washed with toluene (3.times.100 ml),and then with hexane (4.times.100 ml) to obtain 6.3 g of a solid whichcontained 2.45% by weight of titanium and 10.7% by weight of di-n-butylsuccinate. The so obtained catalyst was then used in the polymerizationof propylene according to the general procedure reported above. Theresults are shown in Table 2.

Example 2

The same procedure disclosed in example 1 was replicated with thedifference that diethyl cyclohexylsuccinate was used instead di-n-butylsuccinate. The characteristics of the catalyst are reported in table 1.The so obtained catalyst was then used in the polymerization ofpropylene according to the general procedure reported above. The resultsare shown in Table 2.

Example 3

The same procedure disclosed in example 1 was replicated with thedifference that diethyl 2-ethyl-2-methylsuccinate was used insteaddi-n-butyl succinate. The characteristics of the catalyst are reportedin table 1. The so obtained catalyst was then used in the polymerizationof propylene according to the general procedure reported above. Theresults are shown in Table 2.

Example 4

The same procedure disclosed in example 1 was replicated with thedifference that diethyl 2,3-diisopropylsuccinate was used insteaddi-n-butyl succinate. The characteristics of the catalyst are reportedin table 1. The so obtained catalyst was then used in the polymerizationof propylene according to the general procedure reported above. Theresults are shown in Table 2.

Example 5

same procedure disclosed in example 1 was replicated with the differencethat diisobutyl 2,3-diisopropylsuccinate was used instead di-n-butylsuccinate. The characteristics of the catalyst are reported in Table 1.The so obtained catalyst was then used in the polymerization ofpropylene according to the general procedure reported above. The resultsare shown in Table 2. TABLE 1 Succinate Ti Ex. Wt % Wt % 1 Di-n-butylsuccinate 10.7 2.45 2 Diethyl cyclohexylsuccinate 13.9 2.6 3 Diethyl2-ethyl-2-methylsuccinate 12.1 2.2 4 Diethyl 2,3-diisopropylsuccinate16.2 3 5 Diisobutyl 2,3-diisopropylsuccinate 19.6 3

TABLE 2 Example Yield XI n. KgPP/gTit Wt % PI. 1 530 96.2 4.7 2 150097.6 4.8 3 2501 97.2 5.0 4 2333 98.5 6.0 5 2533 98.8 5.5

1. A solid catalyst component for the (co)polymerization of olefinscomprising titanium, magnesium, halogen and a succinate which isobtained by a process comprising the following steps: (a) dissolving ahalide of magnesium in a solvent system comprising an organic epoxycompound or an organic phosphorus compound and optionally an inertdiluent, thereby forming a solution; (b) mixing the solution of step (a)with a titanium compound, thereby forming a mixture; (c) precipitating afirst solid from the mixture of step (b) in the presence of at least oneof a succinate and an auxiliary precipitant; (d) if a succinate is notused in step (c), contacting the first solid of step (c) with asuccinate, thereby forming a second solid, and (e) treating the solid ofstep (c) or (d) with a titanium compound optionally in the presence ofan inert diluent.
 2. The catalyst component according to claim 1 whereinthe auxiliary precipitant is selected from organic anhydrides, organicacids, ethers, aldehydes and ketones.
 3. The catalyst componentaccording to claim 1 wherein the auxiliary precipitant is selected fromacetic anhydride, phthalic anhydride, succinic anhydride, maleicanhydride, pyromellitic dianhydride, acetic acid, propionic acid,butyric acid, acrylic acid, methacrylic acid, acetone, methyl ethylketone, benzophenone, dimethyl ether, diethyl ether, dipropyl ether,dibutyl ether, diamyl ether and mixtures thereof.
 4. The catalystcomponent according to claim 1 wherein the halide of magnesium ismagnesium dichloride.
 5. The catalyst component according to claim 1wherein the organic epoxy compound is selected from the group consistingof oxides of aliphatic olefins, aliphatic diolefins, halogenatedaliphatic olefins, halogenated aliphatic diolefins, glycidyl ethers, andcyclic ethers, the organic epoxy compound having 2-8 carbon atoms. 6.The catalyst component according to claim 1 wherein the titaniumcompound has the formula TiX_(n)(OR)_(4-n) wherein X is a halogen, eachR is independently a hydrocarbyl group and n is an integer of from 0 to4.
 7. The catalyst component according to claim 6 wherein the titaniumcompound is selected from the group consisting of titaniumtetrachloride, titanium tetrabromide, titanium tetraiolide, tetrabutoxytitanium, tetraethoxy titanium, chlorotriethoxy titanium,dichlorodiethoxy titanium, and trichloroethoxy titanium.
 8. The catalystcomponent according to claim 1 wherein the succinate is selected fromthose having the formula (I):

wherein the radicals R₁ and R₂, equal to or different from each other,are a C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl,arylalkyl or alkylaryl group, optionally containing heteroatoms; theradicals R₃ to R₆ equal to or different from each other, are hydrogen ora C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkylor alkylaryl group, optionally containing heteroatoms, further, theradicals R₃ to R₆ can be linked together to form a cycle.
 9. Thecatalyst component according to claim 8 wherein in the succinate offormula (I), R₁ and R₂ are C₁-C₈ alkyl, cycloalkyl, aryl, arylalkyl andalkylaryl groups.
 10. The catalyst component according to claim 8wherein in the succinate of formula (I), R₃ to R₅ are hydrogen and R₆ isa branched alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl radicalhaving from 3 to 10 carbon atoms.
 11. The catalyst component accordingto claim 8 wherein in the succinate of formula (I), at least tworadicals from R₃ to R₆ are different from hydrogen and are selected fromC₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl oralkylaryl group, optionally containing heteroatoms.
 12. The catalystcomponent according to claim 11 wherein in the succinate of formula (I),the at least two radicals from R₃ to R₆ different from hydrogen arelinked to different carbon atoms.
 13. A catalyst for the polymerizationof olefins CH₂═CHR, in which R is hydrogen or a hydrocarbyl radical with1-12 carbon atoms, comprising the product of the reaction between: (A) asolid catalyst component comprising titanium, magnesium, halogen and asuccinate which is obtained by a process comprising the following steps:(a) dissolving a halide of magnesium in a solvent system comprising anorganic epoxy compound or an organic phosphorus compound and optionallyan inert diluent, thereby forming a solution; (b) mixing the solution ofstep (a) with a titanium compound, thereby forming a mixture; (c)precipitating a first solid from the mixture of step (b) in the presenceof at least one of a succinate and an auxiliary precipitant; (d) if asuccinate is not used in step (c), contacting the first solid of step(c) with a succinate, thereby forming a second solid, and (e) treatingthe solid of step (c) or (d) with a titanium compound optionally in thepresence of an inert diluent; (B) an alkylaluminum compound; and,optionally, (C) at least one electron-donor compound (external donor).14. The catalyst according to claim 13 in which the alkylaluminumcompound (B) is a trialkyl aluminum compound.
 15. The catalyst accordingto claim 13 in which the external donor (C) is a silicon compound offormula R_(a) ⁵R_(b) ⁶Si(OR⁷)_(c), where a and b are integers from 0 to2, c is an integer from 1 to 4 and the sum (a+b+c) is 4; R⁵, R⁶ and R⁷are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionallycontaining heteroatoms.
 16. The catalyst according to claim 15 in whicha is 1, b is 1 and c is
 2. 17. The catalyst according to claim 15 inwhich at least one of R⁵ and R⁶ are branched alkyl, cycloalkyl or arylgroups with 3-10 carbon atoms optionally containing heteroatoms and R⁷is a C₁-C₁₀ alkyl group.
 18. The catalyst according to claim 15 in whicha is 0, c is 3 and R⁶ is a branched alkyl or cycloalkyl group and R⁷ ismethyl.
 19. A process for the (co)polymerization of olefins CH₂═CHR, inwhich R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms,carried out in the presence of a catalyst comprising the product of thereaction between: (A) a solid catalyst component comprising titanium,magnesium, halogen and a succinate which is obtained by a processcomprising the following steps: (a) dissolving a halide of magnesium ina solvent system comprising an organic epoxy compound or an organicphosphorus compound and optionally an inert diluent thereby forming asolution; (b) mixing the solution of step (a) with a titanium compound,thereby forming a mixture; (c) precipitating a first solid from themixture of step (b) in the presence of at least one of a succinate andan auxiliary precipitant; (d) if a succinate is not used in step (c),contacting the solid of step (c) with a succinate, thereby forming asecond solid, and (e) treating the solid of step (c) or (d) with atitanium compound optionally in the presence of an inert diluent; (B) analkylaluminum compound; and, optionally, (C) at least one electron-donorcompound (external donor).
 20. The catalyst according to claim 17wherein the C₁-C₁₀ alkyl group is methyl.